Modification of the properties of fibrous materials



- June 11, 1957 V A. LOWE E AL MODIFICATION OF THE PROPERTIES OF FIBROUSMATERIALS Filed Nov. 30, 1954 FIBROUS 4 MATERIAL HYDRAZIDE BATH FFORMALDEHYDE BATH L l NITRITE BATH ACID TREATMENT DRYING F I MECHANICALTREATMENT I L- I r 1 I BAKING I I INVENTOII ARTHUR LOWE GERALD WILL JAMSBYWQMQT ATTORNEY5 Unite MODIFICATION OFTHE PROPERTIES OF FIBROUSMATERIALS Application November 30, 1954, Serial No. 472,208

Claims priority, application GreatBritain November 24, 1954 7 Claims.or. 117-1395 This invention relates to the modification of theproperties of fibrous materials and more particularly to the treatmentof textiles, leather, paper, etc. with organic hydrazides and nitrousacid, and, preferably, formaldehyde.

According to the present invention we provide a process for themodification of the properties of fibrous materials which comprisestreating said materials with an organic hydrazide and with nitrous acidand,.preferably, with formaldehyde and subsequently drying the treatedmaterial.

Any organic hydrazide, containing one or more hydrazide groups in themolecule, can be used in the process of this invention. Thus for examplethere can be used the dihydrazides of succinic, glutaric, adipic andsebacic acids, hexadecane-l:l6-dicarboxylic dihydrazide, benzoic acidhydrazide, isophthalic acid dihydrazide or citric acid trihydrazide. p 1The treatment of the fibrous material with the'hydrazide and nitrousacid may be accomplished for example by padding through anaqueous-solution or dispersion of an acid salt of the hydrazide, dryingand then padding through an aqueous solution of an alkali salt ofnitrous acid. Alternatively the hydrazide salt impregnated material maybe sprayed with a solution of a nitrite. Y

The application of hydrazide and nitrite may be accomplishedsimultaneously by padding through a solution or dispersion containingboth the hydrazide and the nitrite. The impregnated material is thendried and treat- :ed with an acid in order to liberate the nitrous acid.

In this application of hydrazide and nitrous acid to the material it isessential in order to obtain the best results, that reaction between thetwo components should occur within the fibre and to this end thecomponents are applied in such forms, as described above, as to ensurethat the active agents are liberated only within the fibrous material.

Suitable concentrations of hydrazide or salt thereof and nitrite in thetreatment baths are from about 0.5% to about 20% so that with a take-upof about 100%, the proportion of hydrazide and nitrite deposited on thefibre is from about 0.5 to about 20%.

The temperature of the treatment baths may vary between C. and 100 C. Itis sometimes convenient to treat the material with the hydrazide saltsolution atelevated temperatures such as 50100 C. and then with thealkali nitrite at lower temperaturessuch as 0 to 20. C.

The modification of the properties of thefibrous material is'achieved bydrying the material after treatment with hydrazide and nitrous acid.Afterdrying, the treated material is preferably baked at a temperatureof from about 50 C. to about 200 C. The time required for the bakingstep, after drying the material, is usually from about 3 minutes toabout half an hour. In some cases, satisfactory results are obtained byconditioning the treated material at room temperature for some hours,with out any. baking stage.

The process of this invention can be applied, with valu- States PatentIc v materials depends upon the particular material treated.

Thus for example viscose rayon fabrics thathave been treated accordingto the process of this inventionhave enhanced dimensional stability.Treated paper is found to possess a greatly increased wet strength.-A'substantial degree of water-repellency may also be imparted tocellulosic materials. Softening agents or substances to give a firmhandle may be incorporated with the hydrazide in order-to give enhancedeffects.

The modification of the properties of the fibrous materials is stillfurther increased by inclusion in the treatment baths of formaldehyde.

The formaldehyde may be added to any of the treatment baths, containing,for example, the hydrazide salt or the nitrite or the mixture ofhydrazide and nitrite. The concentration of formaldehyde in thetreatment baths is conveniently from about 1% to 15% by weight, so thatwith a take-up of about the amount of formaldehyde deposited on thefibre is from about -1% to about 15 by weight of the fibre.. 1

The enhancement of effect produced by the use of formaldehyde is mostmarked when at least some of the hydrazide used is a poly-hydrazide suchas a dior trihydrazide. V v 1 Furthermore, the .treatment process ofthis invention may be combined with other treatments of the fibrousmaterial and these other treatments are thereby modified, improved,enhanced in effect or rendered more permanent;- Such other treatmentsare for example mechani cal finishes applied to cotton fabrics such ascalendering, embossing, beetling, rippling, pressing or schreinering.The effects so obtained vary according to theprocess; thus'for examplethere may be produced lustre, glaze and finishes known as moire or cite.Normally these processes are very sensitive to moisture, and they may besubstantially diminished or even destroyed by water or by aqueous.treatments, for example laundering or steam pressing processes such as.are common in the final stages of garment manufacture. These finishesmay be rendered more permanent, especially to the-effect of water, bythe simultaneous v or subsequent treatment according to the proces'softhe present invention.

The chemical processes involved in the process of the invention arepresumably first the interaction of the hydrazide with nitrous acidto-form the corresponding azide followed by decomposition of the azideon heating to generate the corresponding isocyanate. The valuableetfects achieved by the treatment of fibrous materials with isocyanatesare well known but it has not hitherto been possible to effect suchtreatment in the case of all isocyanates with the use of aqueoussolutions or dispersions. Moreover the results obtained by the processof the present invention are superior to those obtainable by any processof the prior art when directed to the I application of the isocyanatecorresponding to that which isformed in any specific case accordingto the foregoing theoretical exposition. The value of the presentinven tion,and the results obtained, does not depend upon the theoreticalexposition which is provided merely as a possible explanation of thenature of the processes involved. a

.We are aware that it has already been proposed to treat textiles andother materials with solutions of an azide in benzene or otherhydrophobic liquid obtained by interacting a hydrazide and nitrous acidin an aqueous medium, and extracting therefrom with the aforementionedhydrophobic solvents. An essential feature of the present invention;however; resides in the interaction of hydrazide and nitrous acid withinthe fibre, since thereby full advantage is taken of the swelling powerof aqueous solutions. It is'well known that in the case of cellulosicmaterials, both natural and synthetic, difiiculty is frequentlyeXperiencedin effecting the desired degree of reaction with reagent-s inorganic solvents owing to their reluctance to absorb the majority oforganic solvents. It is sometimes necessary to promote the desiredadditional reactivity by first wetting the materials with water andthenremoving the water by azeotropic distillation. By the process of theinvention the liberationof the isocyanate is achieved within the fibreunder conditions favouring maximum penetration and the effect of thereagent is accordingly increased over that given by. the application ofthe corresponding azide or isocyanate in solution in organic solvents.

According to a further feature of the invention an amide, an amidine oran aminotriazine may be applied to the material during the treatmentwith the hydrazide so as to be present within the material during thesubsequent baking treatment. Particularly suitable amides (which includethioamides, carboxylic acid amides and sulphonarnides) are urea,dithiourea and acetamide, benzene sulphonarnide or p-toluenesulphonamide; suitable amidines include cyanamide, guanidine andaminoguanidine; andsuitable aminotriazines include melamine. Theimprovement which is brought about by these amides, amidines oraminotriazines is demonstrated by the firmer handle of the finishedmaterial and the greater resistance of the mechanical eifect to washing.

-The drawing illustrates a flow sheet for the present process. Thosesteps enclosed by broken lines are not essential to the process butrepresent additional embodiments as described above. While a separateformaldehyde treatment has been shown, as discussed above, this reagentmay be included in the hydrazide bath or the nitrite bath just as thehydrazide bath and nitrite bath may be combined if desired. LlkW1S,'thBMechanical Treatment is shown in the preferred position. Theinvention isillustrated but not limited by the following examples in which parts andpercentages are by weight, unless otherwise indicated.

Example 1 'A cotton fabric is immersed ina solution of parts ofsebacic-acid dihydrazide dihydrochloride in 95 parts of water'a't 60C.'and squeezed between rollers so that the uptake of the solution is75% of thedry weight of the fabric. The fabric is then dried at 50 'C.and then immersed ina solution'of 5 parts of sodium'nitrite in 95. partsof water and squeezed between rollers so that the uptake of the solutionis 75% of the dry weight Example 2 A cotton fabric is immersed in adispersion containing Sparts of sebacic acid dihydrazide, 3 parts ofsodium nitrite, 0.3 part of the disodium salt of methylene dinaphthylenesulphuric acid and 91.7 parts of water and squeezed between rollers sothat the uptake of the solution is 75% of the dry weight of the fabric.The fabric is dried at 50 C. and then immersed in a solution of 5 partsof acetic acid in 95 parts of water and squeezed between rollers so thatthe uptake of the solution is 75% of the dry weight. The fabric isthendried at 2030 4 C. so that it contains 10-15% of water and is thenglazed by treatment in .a known manner on a calender at 200 C. A heattreatment at 150 C. for 3 minutes follows and finally the fabric iswashed for 10 minutes in 2% aqueous soap solution at 80 C. followed bywashing in water and drying.

The resulting glaze is resistant to boiling soap solutions.

Example 3 A viscose staple fibre plain weave fabric is immersed in asolution containing 3 parts of adipic dihydrazide dihydrochloride and 97.parts of water and squeezed between rollers so that the uptake of thesolution is 80% of the dry weight of the fabric. The fabric is thenstretched back to its former dimensions on a pin stenter and sprayed inthis state with a solution of 10 parts of sodium nitrite in 90 parts ofwater so that the whole material is thoroughly wetted out and hasincreased in weight by 100%. The treated material is then dried andbaked by heating in an oven at 125. C. vfor 10 minutes. a

The effect of these treatments is shown in the following table givingthe amount of shrinkage obtained by washing the fabric in aqueoussolutions of 0.1% soap and 0.1% soda ash at the boil for 1 hour. 7

. Area shrinkage, percent Untreated fabric .a 16.9 Treated fabric 7.4

Exampt'e 4 A viscose staple fibre plain weave fabric is immersed in asolution containing 5 parts of sebacic dihydrazide hydrochloride and 95parts of water at 60 C. and squeezed between rollers sothat the uptakeof the solution is 75% of the dry weight of the fabric. The fabric isthen dried at 20,50 C. and then'immersed in a solution of 5 parts ofsodium nitrite in 95 parts of water and squeezed between Example 5 'Asheet of absorbent paper is passed through a solution of 1 part ofsebacic dihydrazide dihydrochloride in 999 parts of water and thensqueezed so that the uptake of the solution is 200% of the dry weight ofthe paper. The paper is dried at C. and then passed through an aqueoussolution'containing 0.1% sodium nitrite. The

material is then dried and baked by heating in an oven at C. for 5minutes. Theresulting paper has a wet strength many times greater thanthe untreated material.

Example 6 A viscose staple fibre plain weave fabric is immersed in a.solution containing 2.5 parts of sebacic acid dihydro- :chloride, 2.5parts ofacetamide and 95 parts of water at 50 C.. and squeezed betweenrollers so that theuptake of solution is 75% of the-dry weight ofthefabric. The

fabric is then 'dried on a pin stenter at 100 C. for 3 minutes and thensprayed on the stenter frame with a solution of 10 parts of sodiumnitrite in 90 parts of water so that the whole of the fabric is evenlywetted. The fabric is then dried and baked on the stenter frame byheating in an oven at C. for' 10 minutes. The etfect of these treatmentsis shown in the following table giving the amount of shrinkage obtainedby washing the fabric in Untreated Treated Example 7 A viscose staplefibre plain weave fabric is immersed in a solution containing parts ofsebacic dihydrazide dihydrochlon'de and 95 parts of water and squeezedbetween rollers so that the uptake of the solution is 75% of the dryweight of the fabric. The fabric is stretched back to its originaldimensions on a pin stenter and dried in an oven at a temperature of 125C. for 5 minutes. The dry fabric is then immersed in an aqueous solutioncontaining 1.6% formaldehyde and 3.0% sodium nitrite and squeezedbetween rollers so that the uptake of the solution is 75% of the dryweight of the fabric. The fabric is stretched to its original dimensionson a pin. stenter and then placed in an oven maintained at a temperatureof 125 C. for 15 minutes. y

The effect of these treatments is shown in the following table givingthe amount of shrinkage obtained by washing the fabric in aqueoussolutions of 0.1% soap and 0.1% soda ash at the boil for 1 hour.

Area shrinkage, percent Untreated fabric 17.3 Treated fabric 5.0

Example 8 A mercerised cotton gaberdine fabric is padded through asolution containing 2.5 parts of sebacic dihydradize dihydrochloride, 3parts of stearic hydrazide hydrochloride and 94.5 parts of water at 80C. and squeezed between rollers so that the uptake of the solution is60% of the dry weight of the fabric. The fabric is then air-dried andpadded through a solution containing 1 part of formaldehyde, 3 par-ts ofsodium nitrite and 96 parts of water at 20 C., squeezed between rollersso that the uptake of the solution is 60% of the dry weight of thefabric and finally placed in an oven maintained at a temperature of 130C. for 10 minutes. The fabric is then rinsed in warm water for 5 minutesand dried. The fabric thus obtained has a high degree ofwater-repellency which is only slightly affected by washing in aqueoussolution of 0.1% soap and 0.1% soda ash at the boil for 1 hour, or bydry cleaning in white spirit for /2 hour.

Example 9 A mercerised cotton gaberdine fabric is padded through asolution containing 2.5 parts of sebacicv dihydrazide hydrochloride, 3parts of stearic hydrazide hydrochloride and 94.5 parts of water at 80C. and squeezed between rollers so that the uptake of the solution is65% of the dry weight of the fabric. The fabric is then air dried andpadded through a solution containing 3 parts-of sodium nitrite and 97parts of water at 20 C., squeezed between rollers so that the uptake ofthe solution is 60% of the dry weight of the fabric and finally placedin an'oven maintained at a temperature of 130 C. for minutes. The fabricis then rinsed in warm water for 5 minutes and dried. The fabric thusobtained has a high degree of water-repellency which is only slightlyaffected by washing in aqueous 0.1% soap solution at 70 C. for 1 hour.

Example 10 A mercerised cotton gaberdine fabric is padded through asolution containing 2.5 parts of sebacic dihydrazide dihydrochloride, 3parts of ll-hydroxystearic hydrazide hydrochloride and 94.5 parts ofwater at 80 C. and squeezed between rollers so that the uptake of thesolution is 60% of the dry weight of the fabric. The fabric is thenair-dried and padded through a solution containing 1 part offormaldehyde, 3 parts of sodium nitrite and 96 parts of water at C.squeezed between rollers so that the uptake of 6 the solution is 60%of'the dry weight of the fabric and finally "placed'in anoven'maintained'at"atemperature of 130 C. for 10 minutes. The fabricis thenrinsedin Warm water for 5 minutes and. dried. The fabric thus obtainedhas a high degreeof water repellency, which is only slightly affected bywashing in an aqueous solution of 0.1% soap and 0.1% sodaash at the boilfor 1 hour,

or by dry cleaning in white spirit for /z hour.

l I i Example 11 r v I A mercerised cotton gaberdine fabric is paddedthrough a solution containing 255 parts of sebacic dihydrazidedihydrochloride, 3 parts of stearic hydrazide hydrochloride and-94.5parts of waterat"- and squeezed between rollers so that the uptakeofthesolution is 60% of the dry weight of the fabric. The;fabric is thenpadded through a solution containing 3 parts of formaldehyde, 9 parts ofsodium nitrite and- 88 parts of water and squeezed between rollers sothat the increase in weight of the fabric is now 100% of the dry weight.The wet fabric is then rinsed thoroughly. in water at 015 C., squeezedbetween rollers to remove as much water as possible and finally placedin an oven maintained at a 7 temperature of 130 C. for 10 minutes. Thefabric thus Example 12 I A viscose staple fibre plain 'weave fabric isimmersed in a solution containing 2.5 parts 'of isophthalic dihydrazidedihydrochloride and 97.5 parts of water and squeezed between rollers sothat the uptake of the solution is 80% of the dry weight of the fabric.The fabric is then stretched back to its former dimensions on a pinstenterand sprayed in this state with a solution of 10 parts of sodiumnitrite in 90 parts of water so that the whole material is thoroughlywetted out and has increased in weight by The treated material is thendried and baked by heating in an oven at C. for 10 minutes. The fabricthus obtained shows good resistance to shrinkage by alkaline washingtreatments.

Example 13 A viscose staple fibre plain weave fabric isimmersed in asolution containing 4 parts of the hydrochloride of polyacrylicpolyhydrazide (obtained by heating ethyl polyacrylate with hydrazidehydrate) and 96 parts of water and squeezed between rollers so that theuptake of the solution is 75 of the dry weight of the fabric. The fabricis then dried at 20-50 C. and then immersed in a solution of 3 parts ofsodium nitrite and 1% of formaldehyde in 96 parts of water and squeezedbetween rollers so that the Y uptake of the solution is 75% of the dryweight. The wet fabric is then stretched to its former dimensions on apin stenter and then dried and baked by heating in an oven at C. for 10minutes. The resulting fabric has a firm full handle and shows gooddimensional stability when subjected to alkaline washing treatments.

Example :14

A plain weave cotton fabric is immersed in a solutionof 4.5 parts ofsebacic dihydrazide dihydrochloride 'in' 95.5 parts of water, squeezedbetween rollers so that the uptake of the rollers is 7 5% of the dryweight of the fabric. The wet fabric is then immersed in a solution of 4parts of sodium nitrite in 96 parts of water, squeezed through rollersso that the weight of the fabric is now twice as great as its dryweight. The fabric is then conditioned to contain 10% of its weight ofmoisture, and embossed according to conventional means. The fabric isthen given a heat treatment of 3 minutes at 140 C. The embossed designproduced is highly resistant to washing in boiling soap solutions.

If desiredthe heat treatment after embossing may be omitted andthe-fabric conditioned at roomtemperature for 24 hfours.- The. resultingembossed design is resistant to washing inboiling soap solutions.

Example 15 A cellulose acetate plain weave fabric is passed through asolution of 4 parts of sebacic dihydrazide dihydrochloride in 96 partsof water at 60 C., squeezed through rollers so that the uptake of thesolution is 50% of the dry weight Example 16 A mercerised cottongaberdine fabric is passed through a solution of" 3 parts of stearichydrazidehydrochloride and 97 parts of water at 70 C. and squeezedbetween roller'sso-that'the uptake of the solution is 60% of the dryweight of the fabric. The fabric is then passed through a solution of 2parts sodium nitrite in 98 parts of water, squeezed between rollers sothat the weight of the wet fabric is now twice that of the dry fabricand finally dried and baked in an oven at 140 C. for 10 minutes. Thefabric is then rinsed in warm water for minutes and dried. The fabricthus obtained has a high degree of water repellency.

Example 17 25 parts of bleached sulphite pulp are suspended in 1500parts of water and disintegrated by vigorous stirring. 12.5 parts of aaqueous solution of aluminium sulphate are added followed by 0.6 part ofsebacic dihydrazide dihydrochloride. After standing at 20 C. for 30minutes, 3 parts of sodium nitrite are added and the suspension isstirred for a further 5 minutes. 3500 parts of water are then added andafter stirring for a further 5 minutes, the mixture is filtered and theresulting paper dried and baked at 115 C. for 10 minutes. Paper preparedby this method has a markedly higher bursting strength than thatprepared when the hydrazide is omitted.

Example 18 A plain weave cloth made up from polyethylene terephthalateyarn is padded through a solution containing 2.5 parts ofsebacic-dihydrazide hydrochloride, 3 parts of stearic hydrazidehydrochloride and 94.5 parts of water at 80 C. and squeezed betweenrollers, the uptake of the solution being 35% of the dry weight of thefabric. The cloth is then dried at 50-60 C. and padded through asolution containing 3 parts of sodium nitrite and 97 parts ofwater at 20C., squeezed between rollers and placed in an oven maintained at atemperature of 120 C. for minutes. The fabric is then rinsed in warmwater and dried. The cloth thus obtained has a high degree of waterrepellency which is only slightly affected by washing in aqueous 0.1%soap solution at 70 C. for 1 hour.

Example I 9 sebacic dihydrazide' dihydrochloride, 3 parts of ll-li'ydroxystearic'hydrazide hydrochloride and 94.5 parts of water at C. andsqueezed between rollers so that the uptake of the solution is 45% ofthe dry weight of the fabric. The cloth is then air dried and paddedthrough a solution containing 1 part of formaldehyde, 3 parts'of sodiumnitrite and 96 parts of water at 20 C., squeezed between rollers so thatthe uptake of the solution is 45% of thedry Weight of the fabric andfinally placed in an oven maintained at a temperature of C. for 10minutes. The fabric is then rinsed in warm water for 5 minutcs'anddried. The fabric thus obtained has a high degree of water repellency.

Example 20 Pelts are immersed in 215% aqueous solution of adipicdihydrazide for 12 hours at a temperature of 1520 C. The pelts are thenfreed from supernatant liquor by decantation and immersed in a 3%aqueous solutionof nitrous acid containing l;6% formaldehyde for 12hours at a temperature of 15 C. After thorough rinsing with water anddrying at 20 C. a tanned leather having a shrink temperature of 87 C. isobtained.

What we claim is:

l. A process for the modification of the properties of fibrous materialsinvolving in situ formation of an organic isocyanate in said fibrousmaterial which comprises impregnating said material with an organichydrazide in a substantially aqueous medium and thereafter formingnitrous acid in said hydrazide impregnated material to produce saidisocyanate.

2. Fibrous materials p'roduced'by the process of claim 1.

3. The process of claim l'further defined by the additional step oftreating said materials with formaldehyde, intermediate saidimpregnation with an organic hydrazide and said forming of nitrous acid.

4. Process for the modification of the properties of fibrous materialsas claimed in claim 1, wherein, after drying, the treated material isbaked at a temperature of from about 50 C. to about 200 C.

5. Process for the modification of the properties of fibrous materialsas claimed in claim 1, wherein at least some of the hydrazide'used is apolyhydrazide.

6. Process for the modification of the properties of fibrous materialsas claimed in claim 1 including the subsequent step consisting ofmechanically treating said fibrous materials.

7. Process for the modification of the properties of fibrous materialsas claimed in claim 1 wherein'a member of the group consisting of anamide, an amidine and an aminotriazine is applied to the material duringthe treatment with the hydrazide.

References Cited in the file of this patent UNITED STATES PATENTS GoldJune 1, 1954

1. A PROCESS FOR THE MODIFICATION OF THE PROPERTIES OF FIBROUS MATERIALSINVOLVING IN SITU FORMATION OF AN ORGANIC ISOCYANATE IN SAID FIBROUSMATERIAL WHICH COMPRISES IMPREGNATING SAID MATERIAL WITH AN ORGANICHYDRAZIDE IN A SUBSTANTIALLY AQUEOUS MEDIUM AND THEREAFTER FORMINGNITROUS ACID IN SAID HYDRAZIDE IMPREGNATED MATERIAL TO PRODUCE SAIDISOCYANATE.